package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.*;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 */
@Slf4j
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {
    @Resource
    private IUserService userService;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private IFollowService followService;

    /*
    * 查询笔记详情：包含笔记、笔记作者、当前用户是否关注
    * */
    @Override
    public Result queryById(Long id) {
        // 1.查询blog
        Blog blog = getById(id);
        if (blog == null) {
            return Result.fail("笔记不存在！");
        }
        // 2.查询发布blog的用户
        queryBlogUser(blog);
        // 3.查询用户是否点赞
        this.isBlogLiked(blog);
        return Result.ok(blog);
    }

    /*
    * 查询是否关注，在redis中查到博客id的点赞用户id的时间戳，则证明已经点赞
    * */
    private void isBlogLiked(Blog blog) {
        // 1.获取登录用户
        UserDTO user = UserHolder.getUser();
        if (user == null) {
            // 用户未登录，无需查询是否点赞
            return;
        }
        Long userId = user.getId();
        Double score = stringRedisTemplate.opsForZSet().score(BLOG_LIKED_KEY + blog.getId(), userId.toString());
        blog.setIsLike(score != null);
    }

    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = this.query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(blog -> {
            this.queryBlogUser(blog);
            this.isBlogLiked(blog);
        });
        return Result.ok(records);
    }

    private void queryBlogUser(Blog blog) {
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }

    /*
    * 关注操作
    * */
    @Override
    public Result likeBlog(Long id) {
        // 1.获取登录用户
        Long userId = UserHolder.getUser().getId();
        // 2.判断当前登录用户是否已经点赞
        String key = BLOG_LIKED_KEY + id;
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        if (score == null) {
            //3.如果未点赞，可以点赞
            //3.1 数据库点赞数+1
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            //3.2 保存用户到Redis的set集合
            if (isSuccess) {
                stringRedisTemplate.opsForZSet().add(key, userId.toString(),System.currentTimeMillis());
            }
        } else {
            //4.如果已点赞，取消点赞
            //4.1 数据库点赞数-1
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            //4.2 把用户从Redis的set集合移除
            if (isSuccess) {
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            }
        }
        return Result.ok();
    }

    /*
    * 关注排行榜前五名
    * */
    @Override
    public Result queryBloglikesById(Long id) {
        // 1.查询TOP5的点赞用户zrange Key 0 4
        Set<String> topId = stringRedisTemplate.opsForZSet().range(BLOG_LIKED_KEY + id, 0, 4);
        if (topId == null || topId.isEmpty()) {
            return Result.ok(Collections.emptyList());
        }
        // 2.解析用户ID
        List<Long> userIds = topId.stream().map(Long::valueOf).collect(Collectors.toList());
        String idStr = StrUtil.join(",", userIds);
        // 3.根据用户id查询用户 where id in (?...) order by field(id,?...)
        List<UserDTO> userDTOS = userService.query()
                .in("id", userIds).last("ORDER BY FIELD(id,"+ idStr +")").list()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());
        // 4.返回
        return Result.ok(userDTOS);
    }

    /*
    * 发送笔记
    * sortedSet实现滚动分页，推送笔记给粉丝
    * */
    @Override
    public Result saveBlog(Blog blog) {
        // 1.获取登录用户
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());
        // 2.保存探店笔记
        boolean isSuccess = save(blog);
        if(!isSuccess){
            return Result.fail("新增笔记失败!");
        }
        // 3.查询笔记作者的所有粉丝 select * from tb_follow where follow_user_id = ?
        List<Follow> follows = followService.query().eq("follow_user_id", user.getId()).list();
        // 4.推送笔记id给所有粉丝
        for (Follow follow : follows) {
            // 4.1.获取粉丝id
            Long userId = follow.getUserId();
            log.info("{}推送笔记给粉丝:{}，博客id为{}", user.getId(),userId,blog.getId());
            // 4.2.推送，以粉丝id为key，笔记id为value，当前时间戳作为score
            String key = FEED_KEY + userId;
            stringRedisTemplate.opsForZSet().add(key, blog.getId().toString(), System.currentTimeMillis());
        }
        // 5.返回id
        return Result.ok(blog.getId());
    }

    // 查询关注的用户的笔记
    @Override
    public Result queryBlogOfFollow(Long max, Integer offset) {
        // 1.获取当前用户ID
        Long userId = UserHolder.getUser().getId();
        // 2.查询收件箱 ZREVRANGEBYSCORE key Max Min LIMIT offset count
        String key = FEED_KEY + userId;
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset,  2);
        // 3.非空判断
        if (typedTuples == null || typedTuples.isEmpty()) {
            return Result.ok();
        }
        log.debug("查询收件箱结果：{}", typedTuples);
        // 4.解析数据：blogId、minTime（时间戳）、offset
        List<Long> ids = new ArrayList<>(typedTuples.size());
        // 初始化 os 为 offset（而非 1）
        int os = offset;
        long minTime = max;
        for (ZSetOperations.TypedTuple<String> tuple : typedTuples) {// 时间戳：5 4 | 4 4 | 4 4 | 4 3
            ids.add(Long.valueOf(tuple.getValue()));
            long time = tuple.getScore().longValue();
            if (time == minTime) {
                os++; // 同一时间戳内偏移量累加
            } else {
                minTime = time;
                os = 1; // 新时间戳重置为 1（已包含当前元素）
            }
        }
        // 5.根据id查询blog
        String idStr = StrUtil.join(",", ids);
        List<Blog> blogs = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();

        for (Blog blog : blogs) {
            // 5.1.查询blog有关的用户
            queryBlogUser(blog);
            // 5.2.查询blog是否被点赞
            isBlogLiked(blog);
        }

        // 6.封装并返回
        ScrollResult r = new ScrollResult();
        r.setList(blogs);
        r.setOffset(os);
        r.setMinTime(minTime);

        return Result.ok(r);
    }

}
